Method and apparatus for transmitting multi-radio power using time division mode

Title: Method and apparatus for transmitting multi-radio power using time division mode.Abstract: A method for multiple wireless power transfer, capable of transmitting power wirelessly to multiple receivers, by using a time division scheme, includes the steps of: (a) allotting exclusive power transmission time for at least one of the multiple receivers; and (b) transmitting the power wirelessly to each of the at least one of the receivers; wherein, during the exclusive power transmission time allotted to an i-th receiver, which is one of the multiple receivers, the receiving state of the i-th receiver is set to ON and those of the other receivers to OFF. In accordance with the present invention, the following effects can be achieved: the PTE of the multiple receivers may be increased and the PTE of each of the receivers may be kept similarly because the power is transmitted only to one receiver by using the time division scheme and thus interference among multiple receivers is eliminated. ...

The Patent Description & Claims data below is from USPTO Patent Application 20120313450, Method and apparatus for transmitting multi-radio power using time division mode.

FIELD OF THE INVENTION

The present invention relates to a method and a system for multiple wireless power transfer using a time division scheme; and more particularly, to multiple wireless power transfer method and system for allotting an exclusive power transmission time to each of multiple receivers and transmitting power wirelessly by setting only a receiving state of a specific receiver to ON during the power transmission time allotted to the specific receiver.

BACKGROUND OF THE INVENTION

Recently, a lot of studies on technologies for wireless power transfer have been conducted and a technology for transmitting power wirelessly in near field range by using a principle including resonance, etc. has been already introduced.

However, if power is transmitted wirelessly to multiple receivers, interference may arise among adjacent receivers. Therefore, it is difficult to transmit power to multiple receivers with high power transmission efficiency and it is also difficult to control to make the difference in the power transmission efficiency among the respective receivers become small.

FIG. 1 represents power transmission efficiency (PTE) if power is transmitted to multiple receivers according to the prior art. More specifically, FIG. 1 expresses the sum and the difference of PTE of two receivers if the power is simultaneously transmitted wirelessly to the two receivers, wherein a square dots graph 110 indicates the sum of PTE of the two receivers and a round dots graph 120 indicates the absolute value of the difference of PTE thereof. By referring to the prior art of FIG. 1, the distance between a transmitter and a first receiver was set to be 0.15 m and that between the transmitter and a second receiver was set to be 0.10 m.

By referring to FIG. 1, it can be confirmed that total power transmission efficiency 110, i.e., the sum of the total power transmission efficiency of the first and the second receivers, appears to be high partially at roughly 13.5 MHz, 13.9 MHz and 15 MHz and it is not high on the whole with high deviations according to frequency ranges. By referring to FIG. 1, it can be also identified that the difference between the respective receivers 120 in PTE, i.e., the absolute value of the difference between the first and the second receivers in the PTE, has a value much greater than zero within a large part of frequency ranges. This means only the PTE of either the first or the second receiver is high and the PTE of each receiver is not uniformly kept.

As shown above, according to the conventional technology for multiple wireless power transfer, there were problems that the whole PTE becomes reduced and even the PTE of each receiver is not uniform. Accordingly, the method and the system for transmitting power wirelessly are necessary to be developed to achieve the high PTE of the multiple receivers and to distribute the PTE of each receiver uniformly.

SUMMARY

OF THE INVENTION

It is an object of the present invention to solve all the problems mentioned above.

It is another object of the present invention to remove any influence due to interference among multiple receivers at the time of transmitting power wirelessly thereto by setting to the singular number the number of receivers to which power is transmitted at the same time in use of a time division scheme.

In accordance with one aspect of the present invention, there is provided a method for multiple wireless power transfer, capable of transmitting power wirelessly to multiple receivers, by using a time division scheme, including the steps of: (a) allotting exclusive power transmission time for at least one of the multiple receivers; and (b) transmitting the power wirelessly to each of the at least one of the receivers; wherein, during the exclusive power transmission time allotted to an i-th receiver, which is one of the multiple receivers, the receiving state of the i-th receiver is set to ON and those of the other receivers to OFF.

In accordance with one aspect of the present invention, there is provided a transmitter included in a multiple wireless power transfer system, capable of transmitting power wirelessly to multiple receivers by using a time division scheme, including: a time division part for allowing a receiving state of an i-th receiver, which is one of the multiple receivers, to be set to ON and receiving states of the other receivers to be set to OFF during exclusive power transmission time allotted to the i-th receiver by allotting the exclusive power transmission time to each of the at least one of multiple receivers; and a wireless power transmission part for transmitting power wirelessly to each of the at least one of the multiple receivers. In accordance with one aspect of the present invention, there is provided multiple receivers, included in a multiple wireless power transfer system, capable of receiving power wirelessly from a transmitter by using a time division scheme, each including: a receiving state controlling part for controlling a receiving state of a specific receiver among the multiple receivers to be set to ON during exclusive power transmission time allotted to the specific receiver and the receiving state of the specific receiver to be set to OFF during the time except the exclusive power transmission time allotted to the specific receiver; and a switching part for shorting a switching circuit connected with load impedance to make it operated at an ON state and opening the switching circuit to make it operated at an OFF state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a drawing representing power transmission efficiency (PTE), if power is wirelessly transmitted to multiple receivers according to the prior art.

FIGS. 2, 3 and 4 are drawings exemplarily showing a configuration of a multiple wireless power transfer system 200 in accordance with one example embodiment of the present invention.

FIG. 5 is a diagram exemplarily illustrating an equivalent model of a receiver according to a receiving state thereof in accordance with one example embodiment of the present invention.

FIG. 6 is a diagram exemplarily showing a procedure for operating the multiple wireless power transfer system 200 in accordance with one example embodiment of the present invention.

FIG. 7 is a drawing exemplarily representing a configuration of a transmitter and a receiver used to perform this experiment.

FIGS. 8 and 9 are diagrams illustrating the PTE of a first receiver measured if power is transmitted wirelessly to two receivers.

FIGS. 10 and 11 are diagrams representing the PTE of a second receiver measured if the power is transmitted wirelessly to the two receivers.

DETAILED DESCRIPTION

OF THE PREFERRED EMBODIMENTS

The detailed description of the present invention illustrates specific embodiments in which the present invention can be performed with reference to the attached drawings.

In the following detailed description, reference is made to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that the various embodiments of the invention, although different, are not necessarily mutually exclusive. For example, a particular feature, structure, or characteristic described herein in connection with one embodiment may be implemented within other embodiments without departing from the spirit and scope of the invention. In addition, it is to be understood that the location or arrangement of individual elements within each disclosed embodiment may be modified without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, appropriately interpreted, along with the full range of equivalents to which the claims are entitled. In the drawings, like numerals refer to the same or similar functionality throughout the several views.

The configurations of the present invention for accomplishing the objects of the present invention are as follows: □

Configuration of Multiple Wireless Power Transfer system

FIGS. 2, 3 and 4 exemplarily represent a configuration of a multiple wireless power transfer system 200 in accordance with one example embodiment of the present invention.

By referring to FIGS. 2, 3 and 4, the multiple wireless power transfer system 200 may include a transmitter 210 and a receiver 220, and more specifically, the transmitter 210 may include a time division part 211, a wireless power transmission part 212 and a communication part 213 and the receiver 220 may contain a receiving state controlling part 221, a switching part 222 and a communication part 223. In accordance with one example embodiment of the present invention, the multiple wireless power transfer system 200 may transmit power only to one receiver 220 at the same time by using a time division scheme, and more specifically, it may allot an exclusive power transmission time to each of the multiple receivers 220 and wirelessly transmit the power to an i-th receiver while it sets only the receiving state of the i-th receiver to ON and the receiving states of the other receivers to OFF during the power transmission time allotted to the i-th receiver.

After the detailed explanation on components of the transmitter 210 of the multiple wireless power transfer system 200 is made, each component of the receiver 220 will be explained at length.

First of all, the time division part 211 of the transmitter 210 in accordance with one example embodiment of the present invention may perform a function of dividing power transmission time for the multiple receivers 220 and allotting the divided respective power transmission time, i.e., each exclusive power transmission time, to each of the receivers 220. As explained later, during a power transmission time exclusively allotted to a specific receiver, only the receiving state of the specific receiver may be set to ON and the receiving states of the other receivers to OFF by the time division part 211 in accordance with one example embodiment of the present invention. In short, the wireless power transmission is made exclusively between the transmitter 210 and the i-th receiver during the power transmission time allotted to the i-th receiver.

More specifically, the time division part 211 in accordance with one example embodiment of the present invention may search the multiple receivers 220 within a scope of wireless power transmission of the transmitter 210, allot each power transmission time exclusively to each of the searched multiple receivers 220, and create each code including information on the exclusive power transmission time. As such, the created code may be transmitted to each of the multiple receivers 220 through the communication part 213.

It is evident that the time division part 211, in accordance with one example embodiment of the present invention, may allot the exclusive power transmission time only to some of the multiple receivers 220 within the scope of wireless power transmission of the transmitter 210.

Next, the wireless power transmission part 212 of the transmitter 210 in accordance with one example embodiment of the present invention may perform a function of transmitting the power wirelessly to the multiple receivers 220, and more specifically, transmitting the power wirelessly to the multiple receivers 220 by using a resonant frequency between the transmitter 210 and the receivers 220.

As explained above, in accordance with one example embodiment of the present invention, because only the receiving state of only one receiver 220 is at the same time set to ON, the power transmission by the wireless power transmission part 212 is made while the transmitter 210 and the receiver 220 are paired in one on one at any time zone.

If the transmitter 210 and the receiver 220 are coupled strongly in a closed space, the resonant frequency between the transmitter 210 and the receiver 220 may be analyzed by the Coupled Mode Theory (CMT), under which the resonant frequency may be divided into even and odd modes when the transmitter 210 and the receiver 220 are coupled. This may be expressed in the following equation:

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